''Celaenia excavata'', the bird dropping spider of

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

and

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

, derives its name from mimicking bird droppings to avoid predators, mainly birds.

Habitat and appearance

The males are much smaller than the females, about 2.5 mm as opposed to 12 mm. The females have up to 13 egg sacs, with about 200 eggs each, strung together with strong threads. Their

toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...

ity is unknown, but may be able to cause mild illness in humans. ''Celaenia excavata'' is found throughout large parts of eastern and southern

and have also been recorded in central Australia; they are also seen in suburban gardens. The egg sacs of the bird-dropping spider are large, marbled brown coloured spheres, each about 12 mm in diameter and containing over 200 eggs. Up to 13 sacs are silked together in a group, beneath which the spider may be found awaiting prey.

Hunting

Its diet consists almost exclusively of male moths, which it hunts at night by mimicking the scent of female moths. The bird dropping spider stays motionless on its web during the day, only hunting for prey at night. It hangs down from a single silk thread and releases a

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

which mimics the

sex Sex is the biological trait that determines whether a sexually reproducing organism produces male or female gametes. During sexual reproduction, a male and a female gamete fuse to form a zygote, which develops into an offspring that inheri ...

smells released by female moths. When a moth comes near, the spider will capture it with its powerful front legs.

Conservation status

Under the

New Zealand Threat Classification System The New Zealand Threat Classification System is used by the Department of Conservation to assess conservation priorities of species in New Zealand. The system was developed because the IUCN Red List, a similar conservation status system, had s ...

, this species is listed as "Introduced and Naturalised" with the qualifier of "Secure Overseas".

References

External links

University of Southern Queensland: Bird dropping spider

{{Taxonbar, from=Q4289148 Araneidae Spiders of Australia Taxa named by Carl Ludwig Koch Spiders described in 1867 Spiders of New Zealand

Habitat and appearance

Hunting

Conservation status

See also

References

External links